U.S. patent number 6,229,434 [Application Number 09/368,325] was granted by the patent office on 2001-05-08 for vehicle communication system.
This patent grant is currently assigned to Gentex Corporation. Invention is credited to Robert C. Knapp, Robert R. Turnbull, Eric J. Walstra.
United States Patent |
6,229,434 |
Knapp , et al. |
May 8, 2001 |
Vehicle communication system
Abstract
A communication circuit for use in a vehicle including a first
electronic module adapted to be coupled to a power supply of the
vehicle, a second electronic module, and an electrical conductor
coupled between the first and second modules to provide a
transmission path through which power may be supplied and through
which bidirectional serial communication is enabled. The first
module supplies power to the second module through the electrical
conductor. The first and second modules transmit serial data to one
another through the electrical conductor. The first and second
modules may also transmit RF signals over the electrical conductor.
The second module may be housed in an outside rearview mirror
assembly while the first module may be disposed inside of the
vehicle. Such a communication system allows independent control of
multiple electrical components in the outside rearview mirror
assembly over a single wire.
Inventors: |
Knapp; Robert C. (Coloma,
MI), Turnbull; Robert R. (Holland, MI), Walstra; Eric
J. (Grand Rapids, MI) |
Assignee: |
Gentex Corporation (Zeeland,
MI)
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Family
ID: |
26949376 |
Appl.
No.: |
09/368,325 |
Filed: |
August 3, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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262651 |
Mar 4, 1999 |
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Current U.S.
Class: |
340/12.3;
307/10.1; 340/12.37; 340/12.5; 340/425.5; 340/538.15; 701/49 |
Current CPC
Class: |
B60Q
1/00 (20130101); B60R 16/0315 (20130101); G08C
19/02 (20130101) |
Current International
Class: |
B60Q
1/00 (20060101); G08C 19/02 (20060101); H04B
001/00 (); B60Q 001/00 () |
Field of
Search: |
;340/310.01,310.06,310.02,425.5,825.06,825.07,825.69,825.72
;701/36,49,53 ;301/10.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Intellon, News Release, "Intellon Corporation Announces
Registration to ISO 90001:1994", May 12, 19999. .
Intellon, White Paper #0032, "OFDM Communications Primer", Mar.
1999. .
Intellon, "Intellon High Speed Power Line Communications", Mar.
1999. .
PLC Trucks web site, "SAE J1587 Networking Using Spread Spectrum
Power Line Communications (PLC) over the DC Power Bus", Jul. 2,
1999..
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Primary Examiner: Crosland; Donnie L.
Attorney, Agent or Firm: Price, Heneveld, Cooper, DeWitt
& Litton Rees; Brian
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 09/262,651, filed on Mar. 4, 1999, and now
pending. The entire disclosure of U.S. patent application Ser. No.
09/262,651 is incorporated herein by reference.
Claims
The invention claimed is:
1. A communication circuit for use in a vehicle, comprising:
a first electronic module adapted to be coupled to a power supply
of the vehicle;
a second electronic module disposed in a housing of an outside
rearview mirror assembly; and
a dedicated electrical conductor coupled between said first and
second modules to provide a transmission path through which power
may be supplied and through which bi-directional serial
communication is enabled,
wherein said first module supplies power to said second module
through said dedicated electrical conductor and wherein said first
and second modules transmit serial data to one another through said
dedicated electrical conductor.
2. The vehicle communication circuit as defined in claim 1, wherein
said first module modulates the power supplied to said second
module by modulating the voltage level applied to said electrical
conductor.
3. The vehicle communication circuit as defined in claim 1, wherein
said first module modulates the power supplied to said second
module by modulating the current delivered to said electrical
conductor.
4. The vehicle communication circuit as defined in claim 1, wherein
said second electronic module is disposed outside of the
vehicle.
5. The vehicle communication circuit as defined in claim 1, wherein
said first vehicle accessory is coupled to a vehicle system
bus.
6. The vehicle communication circuit as defined in claim 1 and
further including a third electronic module coupled to said second
electronic module by a second dedicated electrical conductor.
7. The vehicle communication circuit as defined in claim 1, wherein
said first module is disposed in a housing of an inside rearview
mirror assembly.
8. The vehicle communication circuit as defined in claim 1, wherein
said first module is disposed in a door of the vehicle.
9. The vehicle communication circuit as defined in claim 1 and
further including a third electronic module coupled to said second
electronic module by a second dedicated electrical conductor,
wherein said third module is disposed in a door of the vehicle.
10. The vehicle communication circuit as defined in claim 1,
wherein said first module is coupled to a vehicle system bus and
generates and transmits control signals to said second module in
response to information transmitted on the vehicle system bus.
11. The vehicle communication circuit as defined in claim 1,
wherein said electrical conductor and said first and second modules
are configured for simultaneous bi-directional communication
between said first and second modules.
12. The vehicle communication circuit as defined in claim 1,
wherein said first module modulates the power supplied to said
second module with serial data.
13. The vehicle communication circuit as defined in claim 1,
wherein at least one of said first and second modules transmit RF
signals over said dedicated electrical conductor.
14. The vehicle communication circuit as defined in claim 13,
wherein said electrical conductor is shielded to minimize
electromagnetic interference.
15. The vehicle communication circuit as defined in claim 13,
wherein at least one of said first and second modules includes a DC
matching and blocking network.
16. The vehicle communication circuit as defined in claim 13,
wherein said second module includes an antenna for receiving RF
signals.
17. The vehicle communication circuit as defined in claim 13,
wherein said second module includes an antenna for transmitting RF
signals received through said electrical conductor.
18. The vehicle communication circuit as defined in claim 1,
wherein said second module is dependent upon said first module for
electrical power.
19. The vehicle communication circuit as defined in claim 1,
wherein said first module modulates the power supplied between a
first voltage level and a second voltage level, where the second
voltage level is lower than the first voltage level and is greater
than zero.
20. The vehicle communication circuit as defined in claim 1,
wherein said first module generates and transmits control signals
to said second module for control of independently operated
electrical components coupled to said second module.
21. A communication circuit for use in a vehicle, comprising:
a first electronic module adapted to be coupled to a power supply
of the vehicle;
a second electronic module disposed in a housing of an outside
rearview mirror assembly; and
a dedicated electrical conductor coupled between said first and
second modules to provide a transmission path through which power
may be supplied and through which serial communication is
enabled,
wherein said first module supplies power to said second module
through said dedicated electrical conductor and wherein said first
and second modules transmit serial data to one another through said
dedicated electrical conductor, and wherein said second module is
dependent upon said first module for electrical power.
22. The vehicle communication circuit as defined in claim 21,
wherein at least one of said first and second modules transmit RF
signals over said electrical conductor.
23. A communication circuit for a vehicle, comprising:
an RF antenna disposed outside of the vehicle;
a first electronic module disposed inside the vehicle and coupled
to a power supply of the vehicle;
a second electronic module coupled to said RF antenna; and
a dedicated electrical conductor coupled between said first and
second modules to provide a transmission path through which power
and RF signals may be transmitted,
wherein said first module supplies power to said second module
through said dedicated electrical conductor and wherein at least
one of said first and second modules transmits RF signals to the
other module through said dedicated electrical conductor.
24. The vehicle communication circuit as defined in claim 23,
wherein said antenna receives RF signals and said second module
transmits the received RF signals to said first module through said
dedicated electrical conductor.
25. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a receiver of a tire
pressure sensing system, said antenna receives RF signals
indicating a sensed tire pressure and transmits the received RF
signals to the receiver through said first and second modules and
said electrical conductor.
26. The vehicle communication circuit as defined in claim 23,
wherein said antenna is disposed in a housing of an outside
rearview mirror assembly.
27. The vehicle communication circuit as defined in claim 23,
wherein said electrical conductor is shielded to minimize
electromagnetic interference.
28. The vehicle communication circuit as defined in claim 23,
wherein at least one of said first and second modules includes a DC
matching and blocking network.
29. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a receiver of a remote
keyless entry system, said antenna receives RF signals including a
command to lock/unlock one or more vehicle doors and transmits the
received RF signals to the receiver through said first and second
modules and said electrical conductor.
30. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a receiver of a trainable
RF transmitter, said antenna receives RF signals including a
command to open one or more garage doors and transmits the received
RF signals to the receiver through said first and second modules
and said electrical conductor during training of the trainable RF
transmitter.
31. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a GPS receiver, said
antenna receives RF signals from a GPS satellite and transmits the
received RF signals to the receiver through said first and second
modules and said electrical conductor.
32. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a garage door opening
transmitter that transmits RF signals to said antenna through said
first and second modules and said electrical conductor.
33. The vehicle communication circuit as defined in claim 23,
wherein said first module is coupled to a transceiver that
transmits/receives RF signals to/from said antenna through said
first and second modules and said electrical conductor.
34. The vehicle communication circuit as defined in claim 23,
wherein said dedicated electrical conductor provides a transmission
path through which bi-directional serial communication is enabled,
and said first and second modules transmit serial data to one
another through said dedicated electrical conductor.
35. The vehicle communication circuit as defined in claim 23,
wherein said second electronic module is disposed outside of the
vehicle.
36. The vehicle communication circuit as defined in claim 23,
wherein said second electronic module is disposed inside of the
vehicle.
37. The vehicle communication circuit as defined in claim 23,
wherein said first vehicle accessory is coupled to a vehicle system
bus.
38. The vehicle communication circuit as defined in claim 23,
wherein said first module is disposed in a housing of an inside
rearview mirror assembly.
39. The vehicle communication circuit as defined in claim 23,
wherein said first module is disposed in a door of the vehicle.
40. The vehicle communication circuit as defined in claim 23,
wherein said second module is disposed in a housing of an outside
rearview mirror assembly.
41. An outside rearview mirror assembly for a vehicle
comprising:
a housing; and
at least two electrical components disposed within or on said
housing, said electrical components are coupled to a dedicated
electrical conductor that provides a transmission path through
which power and serial data signals may be collectively transmitted
to said electrical components, said electrical components are
independently controlled as a result of the transmittal of selected
serial data signals transmitted through said transmission path.
42. The outside rearview mirror assembly as defined in claim 41 and
further including a control circuit disposed within or on said
housing and coupled to said electrical components and to said
electrical conductor such that said electrical components are
coupled to the electrical conductor through said control circuit,
said control circuit transmits control signals to said electrical
components in response to serial data signals transmitted through
said transmission path such that said electrical components being
independently controlled as a result of the transmittal of selected
serial data signals transmitted through said transmission path.
43. The outside rearview mirror assembly as defined in claim 42,
wherein said electronic controller receives power from a power
supply through said transmission path and wherein the power
supplied through the transmission path is modulated with the data
signals.
44. The outside rearview mirror assembly as defined in claim 43,
wherein said control circuit supplies power to at least one of said
electrical components.
45. The outside rearview mirror assembly as defined in claim 42,
wherein said control circuit is coupled to a second electrical
conductor through which said control circuit receives power.
46. The outside rearview mirror assembly as defined in claim 45,
wherein said control circuit supplies power to said electrical
components.
47. The outside rearview mirror assembly as defined in claim 41,
wherein said electrical components include any two or more of the
following components: an electrochromic mirror, a glare detection
sensor, a turn signal indicator, an exterior security lamp, a
mirror heater, an RF antenna, an RF receiver, an RF transmitter, a
mirror positioning mechanism, a mirror folding mechanism, a
temperature probe, a GPS antenna, a GPS receiver, a blind spot
detector, and a road/lane edge sensor.
48. An inside rearview mirror assembly for a vehicle
comprising:
a housing; and
a control circuit disposed within or on said housing and coupled to
a dedicated electrical conductor that provides a transmission path
through which power and serial data signals may be transmitted to
at least two independently operable electrical components of the
vehicle that are coupled to the dedicated electrical conductor,
said control circuit serially transmits data signals through said
transmission path to control the operation of the electrical
components.
49. The inside rearview mirror assembly as defined in claim 48,
wherein said control circuit receives signals from at least one of
the electrical components through said electrical conductor.
50. The inside rearview mirror assembly as defined in claim 48,
wherein the electrical components to which said control circuit is
coupled include any two or more of the following components: an
electrochromic mirror, a glare detection sensor, a turn signal
indicator, an exterior security lamp, a mirror heater, an RF
antenna, an RF receiver, an RF transmitter, a mirror positioning
mechanism, a mirror folding mechanism, a temperature probe, a GPS
antenna, a GPS receiver, a blind spot detector, and a road/lane
edge sensor.
51. The inside rearview mirror assembly as defined in claim 48,
wherein the electrical components to which said control circuit is
coupled include any two or more of the following components: window
switches, mirror position switches, heater switches, door
open/close switches, seat movement switches, a trunk release
switch, and a gas tank door release switch.
52. The inside rearview mirror assembly as defined in claim 48,
wherein said control circuit is coupled to a vehicle system
bus.
53. The inside rearview mirror assembly as defined in claim 48 and
further including an RF receiver disposed in said mirror housing
and coupled to said control circuit to receive RF signals through
the electrical conductor.
54. The inside rearview mirror assembly as defined in claim 48 and
further including an electrochromic mirror disposed in said housing
and electrically coupled to said control circuit.
55. The inside rearview mirror assembly as defined in claim 48,
wherein said control circuit supplies power to the electrical
components.
56. The inside rearview mirror assembly as defined in claim 55,
wherein said control circuit supplies power to the electrical
components through a second electrical conductor.
57. The inside rearview mirror assembly as defined in claim 55,
wherein said control circuit supplies power through said electrical
conductor and modulates the supplied power with serial data.
58. An electronic door module assembly for a vehicle comprising a
control circuit disposed in a door of the vehicle and coupled to a
dedicated electrical conductor that provides a transmission path
through which serial data signals may be transmitted to at least
two independently operable electrical components of the vehicle
that are coupled to the electrical conductor, said control circuit
serially transmits data signals through said transmission path to
control the operation of the electrical components, wherein the
electrical components to which said control circuit is coupled
include any two or more of the following components: an
electrochromic mirror, a glare detection sensor, a turn signal
indicator, an exterior security lamp, a mirror heater, an RF
antenna, an RF receiver, an RF transmitter, a mirror positioning
mechanism, a mirror folding mechanism, a temperature probe, a GPS
antenna, a GPS receiver, a blind spot detector, and a road/lane
edge sensor.
59. An electronic door module assembly for a vehicle comprising a
control circuit disposed in a door of the vehicle and coupled to a
dedicated electrical conductor that provides a transmission path
through which serial data signals may be transmitted to at least
two independently operable electrical components of the vehicle
that are coupled to the electrical conductor, said control circuit
serially transmits data signals through said transmission path to
control the operation of the electrical components, wherein said
control circuit is coupled to any two or more of the following
components: window switches, mirror position switches, heater
switches, door open/close switches, seat movement switches, a trunk
release switch, and a gas tank door release switch.
Description
BACKGROUND OF THE INVENTION
The present invention relates to intra-vehicular communication
systems, and more particularly, to arrangements for communicating
data and supplying power through the same interface in a
vehicle.
Demands for communication systems within vehicles have increased
with greater use of electronic modules for a multitude of
functions. Moreover, the increasing demand for data transmission
within a vehicle creates a problem for managing wiring among
functional modules. For example, many wires are typically needed to
accommodate the power and communication requirements of an internal
controller, an outside mirror position switch in a door panel, and
the outside mirror itself. This is especially so if the outside
mirror assembly includes several electrical components having
differing functions, such as turn signal indicators, mirror
positioners, an electrochromic mirror, RF antennas, a glass heater,
security lights, and road/lane edge location sensors. If an outside
mirror assembly included all these components and also included a
mirror position memory feature, as many as 20 wires may be required
to be run to the outside mirror. Good wire management suggests that
it is desirable to reduce as much as possible the number of wires
that must be run to the outside mirror assembly and to other
electronic modules in the vehicle as well.
To reduce some of the wiring required for much of the electronic
modules in an automobile, many automobiles have a dedicated bus for
electrical signals related to the power train, and in addition,
have at least one CAN or J1850 type system bus for other power
demands within the vehicle such as locks, windows, HVAC, and the
like. With such bus communication systems, however, each electronic
module separately receives power from a power supply of the
vehicle, such as the vehicle battery or ignition. Thus, in addition
to the bus wiring, separate wiring must be run to each module and
electrical component to provide power.
While replacing discrete wiring systems with bus systems has
significantly reduced vehicle manufacturing and material costs,
there are some situations in which it has generally not been
desirable to replace discrete wiring with a connection to the CAN
or J1850 vehicle system bus. For example, running the vehicle
system bus to the exterior of the vehicle for connection to an
outside mirror assembly or to any other electronic module outside
the vehicle may compromise vehicle security. More specifically,
commands to unlock the vehicle doors and deactivate the vehicle
alarm system are typically transmitted over the vehicle system bus.
If this bus were run to an electronic module outside the vehicle, a
thief could readily gain access to the bus and transmit a command
on the bus causing the doors to unlock and the alarm to deactivate.
For this reason alone, manufacturers have not connected the
electronic module in an outside rearview mirror assembly to a bus,
but instead have used a significant number of discrete wires to
enable independent control of all the functional components in the
assembly.
It is known to use ordinary residential power lines to transmit
data in a building. Such communication is affected by superimposing
data signals on a power line using orthogonal frequency division
multiplexing to accommodate noise and other interference in the
power line. It is further known to apply this technology to data
transmission in a tractor-trailer combination over the existing DC
power bus in order to avoid extra wires beyond the standard SAE
J560 connector. This data transmission technique, however, does not
address the situation often found in automobiles where there is
insufficient bandwidth to carry both power and data simultaneously
or where using the vehicle bus would compromise security as in
communication with an outside mirror. Also, if such a data
transmission technique were used in an automobile, the resultant
system would produce unacceptable levels of electromagnetic
interference (EMI) since the data signals would be transmitted
through the unshielded power wiring that runs through most of the
vehicle. There remains a need for a bi-directional communication
system, especially between the inside of the vehicle and the
outside of the vehicle, which will accommodate a solution to the
foregoing problems.
An additional problem caused by increasing vehicle complexity
arises from the use vehicular windows, which incorporate low-E
metallic coatings in order to reduce solar heating inside vehicles.
While this feature has been effective in solar control, it has the
unfortunate side effect of RF shielding the interior of the
vehicle. As a result, the effectiveness of RF-based systems where
the antenna is located in the interior of the vehicle, such as
remote keyless entry, garage door openers, and tire pressure
monitoring systems, is reduced.
SUMMARY OF THE INVENTION
One aspect of the present invention is directed to an arrangement
for communicating between at least two modules mounted to a
vehicle. A power conductor associated with one of the modules
delivers electrical power between them, with one of them being
dependent upon the other for power. In a preferred embodiment, the
second module is an outside mirror module. A control arrangement,
responsive to the first module (which can be an inside mirror
module), selectively modulates an amount of electrical power
delivered. In this manner, information may be transmitted through
the power conductor between the first and second modules.
According to another embodiment, the communication circuit
comprises: an RF antenna disposed outside of the vehicle, a first
electronic module disposed inside the vehicle and coupled to a
power supply of the vehicle, a second electronic module coupled to
the RF antenna, and a dedicated electrical conductor coupled
between the first and second modules to provide a transmission path
through which power and RF signals may be transmitted. The first
module supplies power to the second module through the dedicated
electrical conductor and at least one of the first and second
modules transmits RF signals to the other module through the
dedicated electrical conductor.
According to yet another embodiment of the present invention, an
outside rearview mirror assembly is provided that comprises a
housing, and at least two electrical components disposed within or
on the housing, the electrical components are coupled to an
electrical conductor that provides a transmission path through
which serial data signals may be collectively transmitted to the
electrical components. The electrical components are independently
controlled as a result of the transmittal of selected serial data
signals transmitted through the transmission path.
These and other features, advantages, and objects of the present
invention will be further understood and appreciated by those
skilled in the art by reference to the following specification,
claims, and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a block diagram illustrating the generic components of a
vehicle communication system according to the invention;
FIG. 2 is a block diagram illustrating an exemplary electronic
module and electrical components as provided in an outside rearview
mirror in accordance with the present invention;
FIGS. 3a and 3b are a schematic diagram illustrating a vehicle
communication system according to a particular embodiment of the
present invention;
FIG. 4 is a schematic diagram illustrating a vehicle communication
system according to a second embodiment of the present
invention;
FIG. 5 is a block diagram illustrating a vehicle communication
system according to a third embodiment of the present
invention;
FIG. 6 is a block diagram illustrating a vehicle communication
system according to a fourth embodiment of the present
invention;
FIG. 7 is a block diagram illustrating a vehicle communication
system according to a fifth embodiment of the present invention;
and
FIG. 8 is a block diagram illustrating a vehicle communication
system according to a sixth embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is applicable to a variety of systems and
arrangements where two modules in a vehicle are connected for
communication by an interface and both power and data are to be
transmitted between them. It has particular relevance where a
vehicle incorporates outside elements, such as electrochromic
mirrors, as transmitting and receiving antennas for simultaneous RF
transmission. The invention has also been found to be advantageous
for use in environments in which an automobile interior is RF
shielded from the outside environment. Yet further, the invention
meets the need where wire management demands in a vehicle require
minimal wiring for transmission of data and power among
intra-vehicle locations.
According to one aspect of the present invention, power and
bi-directional data communication are provided over a single wire
and ground pair to a module located outside the vehicle, such as an
outside mirror. In addition to power and bi-directional serial
data, bi-directional RF signals (if coaxial cable or other RF cable
is used) may be simultaneously sent over the same wire.
According to one embodiment of the present invention, a transmitter
and power supply are located in the inside rearview mirror housing
(or any other convenient location within the vehicle interior such
as a door or roof module). It will be understood that "inside the
vehicle" or the vehicle interior includes any location within the
principal exterior shell of the vehicle, such as a passenger
compartment, a trunk, an engine compartment, and the inside of a
door or other exterior panel. Conversely, "outside the vehicle" or
the vehicle exterior includes any location outside the principal
exterior shell, such as outside mirrors, antennas, attachments,
bumpers, grills, spoilers, and the like. In the present embodiment,
a microprocessor in the inside mirror modulates power to the
outside mirror briefly to transmit data. When the power to the
outside mirror is modulated, a capacitor in the outside mirror
provides needed power. In one embodiment, the power supply
modulates between two levels, e.g., 6 V and 8 V, to provide data
communication while maintaining a continuous supply of power to the
outside mirror module. Any additional power needed by the outside
mirror can be supplied by the capacitor. This power supply and data
transmission circuit also provides suppression of transient
voltages present in automotive power systems, reducing the size and
weight of the outside mirror electronics by eliminating the need
for redundant protection circuitry.
In a first embodiment, transmission of data to the inside mirror is
accomplished by means of a current loop. A current source in the
outside mirror modulates the supply current drawn by the outside
mirror module. Data is detected by a current sense amplifier in the
inside mirror. Depending upon the modulation method that is chosen
for the transmissions to and from the inside mirror, simultaneous
bi-directional communication is possible.
Referring now to the drawings, FIG. 1 illustrates in block form
basic components common to some of the embodiments of the
invention. A first module 103 is connected to a second module 105
by an interface consisting of an electrical conductor 114. Power is
supplied over electrical conductor 114 between the first and second
modules, and during periods when the power is modulated, data is
transmitted over the same conductor 114. Any of a number of
well-known coding schemes for data transmission can be employed.
For example, PWM, frequency modulation, or asynchronous serial data
transmission can be used for data transmission as the power is
modulated.
FIG. 2 shows an example of how the present invention may be
implemented to provide serial communication to an outside rearview
mirror assembly including a plurality of different electrical
components. As shown in FIG. 2, second module 105 may be an outside
mirror module. Inside module 103 may be any electronic module
located inside the vehicle, such as an inside rearview mirror
module, a door module, an instrument panel module, or a roof
module. Inside module 103 may receive power from the vehicle
battery 12 or alternatively from vehicle ignition 14. Inside module
103 may be interfaced with one or more electrical components 16
depending upon where module 103 is located. For example, if inside
module 103 is a door module, it would interface with door
lock/unlock and window open/close switches and/or door lock and
window actuators and optionally, seat movement switches, door
open/close switches, a trunk release switch, a gas tank door
release switch, mirror position switches, and heater switches. If
inside module 103 is in inside rearview mirror module, it would
interface with electrical components 16 such as an electrochromic
mirror, an electronic compass, light sensors, a temperature sensor,
a remote keyless entry (RKE) receiver, a GPS receiver, a tire
pressure monitoring receiver, a garage door opener transmitter,
etc. Inside module 103 may additionally be coupled to a vehicle
system bus such as a CAN or J1850 bus.
Outside mirror module 105 is employed to control or otherwise
convey command signals to a plurality of electrical components that
are disposed within or on the housing of the outside rearview
mirror assembly. Such electrical components may include any one or
more of the following: an electrochromic mirror 20; a mirror
positioning mechanism 22; a mirror heater 24; an automatic mirror
folding mechanism 26; a turn signal indicator 28; a road/lane edge
location sensor 30; one or more security lights 32; an RF antenna
34; an RF transceiver, receiver, or transmitter 36 having an
antenna 38; a glare detection sensor 44; a temperature probe 46; a
GPS antenna 48; a GPS receiver 50; and a blind spot detector
52.
Outside mirror module 105 is preferably coupled to inside module
103 by a single electrical conductor 114. Inside module 103 could
then supply power, data, and RF signals to outside mirror module
105 over this single electrical conductor. Further, outside mirror
module 105 could transmit data back to inside module 103 via
conductor 114. Such data may include any RF signals received by
antenna 34 (which may include tire pressure information, RKE
commands, GPS data, etc.), data received by receiver 36, road/lane
edge location sensor output signals, glare detection signals, blind
spot detection signals, outside temperature, and/or any data
transmitted from a third electronic module 42, which may be coupled
to outside mirror module 105. Outside mirror module 105 need not be
dependent upon inside module 103 for the supply of operating power.
It is possible to provide a separate power line connection from
module 105 directly to vehicle battery 12 or vehicle ignition 14.
Alternatively, module 105 may receive its operating power from
inside module 103 via a second electrical conductor 40. With such a
configuration, modules 103 and 105 may communicate directly over
conductor 114 without modulating the power that is supplied to
outside mirror module 105.
FIGS. 3a and 3b show a vehicle communication system comprising a
first module 103 and a second module 105 connected by an interface
114 according to one embodiment of the present invention. More
particularly for this embodiment, the first module 103 is located
inside the vehicle and the second module 105 is located outside the
vehicle as an outside mirror circuit with an electrochromic
element. A power source 100 (FIG. 3a), associated with inside
module 103 and which includes transistors Q1 and Q2, provides
regulated power to the outside mirror circuit 105. Power is
modulated when an input signal drives the OEC_DATA_OUT line between
logic "HIGH" and "LOW" states.
In order to detect transmissions from the outside mirror circuit
105, a current sensing amplifier 102 in the first module 103 acts
as a receiver for receiving data transmitted by the outside mirror
circuit 105. This current sensing amplifier 102 includes a resistor
R8, an operational amplifier U1, and associated circuitry. Ferrite
beads E1, E2, and E3 or RF chokes in the power and data path
isolate the RF signals from the rest of the circuitry and prevent
signal loss. Current sensing amplifier 102 may also be used for
diagnostic functions, such as determining whether there is a short
or open circuit. It will also be appreciated by those skilled in
the art that other ways of transmitting data may be used to
transmit data from second module 105 back to first module 103. For
example, second module 105 may use the voltage stored on a
capacitor to vary the voltage appearing on conductor 114 and
thereby communicate with first module 103.
In one implementation, a voltage regulator powers a microprocessor
or other logic located in the outside mirror circuit 105. In the
implementation depicted in FIG. 3b, diodes D1 and D4, resistor R15,
and capacitors C8 and C4 form a voltage regulator 104 for this
purpose. It will be appreciated, however, that certain types of
loads do not require logic and can be operated directly from the
point labeled LED_POWER. Examples of these types of loads include,
for instance, exterior security lamps, turn indicators, and
preamplifiers.
An optional preamplifier 106 in the outside mirror circuit 105
facilitates the use of relatively inexpensive twisted pair wiring
for RF reception. If bi-directional RF transmission is desired, a
switching diode or other switch can be used to bypass the
preamplifier during transmissions from the first module 103 inside
the vehicle. One example of an application that would benefit from
this arrangement is a garage door opener transmitter located in an
inside mirror combined with a remote keyless entry system.
In the outside mirror circuit 105, an operational amplifier U2 and
its associated circuitry form a data comparator 108 used to detect
power interruptions. This comparator 108 can be implemented using,
for example, a microprocessor or a dedicated logic circuit. A
resistor R3 and a transistor Q3 form a current source 110, which is
used to transmit data from the outside mirror circuit 105 to the
first module 103.
A DC blocking and matching network 112 formed by capacitors C15 and
C1 and inductor L1 isolates the power and data signals from the
electrochromic element. The capacitor C15 performs DC blocking and
RF coupling. The inductor L1 and the capacitor C1 form an RF
matching network to match the antenna, which is implemented here as
the electrochromic element. It will be understood that other
antenna structures, such as a one-quarter wave or helical
structure, could be used in the outside mirror circuit 105 as well.
While FIG. 3b depicts a particular topology for implementing the
matching network 112, it will be appreciated by those skilled in
the art that any of a variety of conventional matching network
topologies can be used to implement the matching network 112.
Topologies other than the one depicted in FIG. 3 may be appropriate
in certain application environments, e.g., particular combinations
of loss requirements, antennas, and transmission lines.
The first module 103 and the outside mirror circuit 105 are
electrically connected using an interface 114. In the embodiment
shown in FIGS. 3a and 3b, the interface 114 is implemented using a
50-ohm coaxial cable W1. It should be noted, however, that the
interface 114 could be implemented using other alternative
conductors, including, but not limited to, twisted pair, single
wire with chassis ground, or other wiring. A line-of-sight optical
connection capable of supplying power and data is also within the
scope of an interface 114 for the invention.
Another example circuit arrangement for implementing a vehicle
communication system according to the invention is illustrated in
FIG. 4. The arrangement of FIG. 4 is considerably simpler than the
system shown in FIGS. 3a and 3b. In this embodiment, a first module
200 comprising a power source 202 and possibly including a
transmitter, a receiver, or both 204, are located inside the
vehicle, such as inside of the rearview mirror assembly. A second
module 206, such as an outside mirror with an electrochromic
element has, as its only circuitry, an optional matching network
208, which includes a capacitor C1 and inductors L2 and L3. The
interface is the RF transmission line 210, which in this case is a
coaxial cable W1. Electrochromic drive power is supplied to the
electrochromic element using the RF transmission line 210. As with
the embodiment depicted in FIGS. 3a and 3b, any of a variety of
matching network topologies can be used to implement the matching
network 208.
By using a single conductor 210 combined with a chassis ground to
transmit data and power to and from the outside mirror module 206,
the number of electrical wires is reduced, compared to that used
with conventional electrochromic mirror systems. Further, using an
outside mirror module as an antenna is particularly advantageous in
vehicles in which a low-E metallic window coating shields RF
transmission from the interior of the vehicle to the exterior.
Moreover, vehicle security is enhanced because the vehicle bus is
retained within the vehicle interior.
In FIG. 5, a further embodiment is illustrated where multiple
inside modules 400-404, interior of the vehicle, are connected to
each other by interfaces 406 and 408, and to a pair of outside
modules 410, exterior of the vehicle, each by another interface
412. In a typical arrangement according to FIG. 5, the interfaces
406 and 408 can comprise the conventional vehicle bus such as CAN
or J1857, and the interface 412 can be a coaxial cable or twisted
wire pair.
FIG. 6 illustrates a particular embodiment of the configurations of
FIGS. 4 and 5. Here, an inside mirror module 500 is connected to a
door module, such as a switch module 502 in both the driver's side
and passenger side doors of an automobile, and then to an outside
mirror module 504 exterior to each side of the vehicle. The
interface 506 between the inside mirror module 500 and the door
modules 502 might typically be a CAN bus and the interface 508
between each door module 502 and the corresponding outside mirror
module 504 is a dedicated wire pair (power and ground). It may be
that each door module 502 is separately powered, but is between the
inside mirror module 500 or the door modules 502, and the outside
mirror modules 504, at least some elements of the outside mirror
modules are powered principally from an inside module. Thus, a
typical arrangement might have the second module dependent upon the
first module for power. Applying the principles of the invention,
the inside mirror module or the door module will have circuitry to
modulate the power delivered to the outside mirror modules, during
which time the outside mirror modules can transmit data to the
corresponding inside module over the dedicated wire pair 508.
In FIG. 7, the arrangement is similar to FIG. 6, except that the
inside mirror 600 is connected directly to the outside mirror
modules 604 by an interface 608, and the door modules 602 are
separately interfaced with the outside mirror modules for other
functions. While the embodiment shown in FIG. 7 may appear to pose
some added security risk by transmitting door unlock commands
through outside mirror module 604, such an arrangement may
nevertheless be desirable since it shortens the path for RF signals
to travel when originating from inside module 600 relative to the
embodiment shown in FIG. 6. Further, security measures may be added
such as a rolling code algorithm that reduce the risks associated
with running such transmission paths outside of the vehicle.
FIG. 8 shows an embodiment where the inside mirror 700 is also
connected to a roof module 702 where, for example, RF antennas may
be located for GPS tracking, radio transmission, cellular telephone
transmission, etc. An interface 704 between them can utilize the
benefits of the invention where data can be transmitted to and from
the roof module while the RF power is modulated.
As will be readily apparent to those skilled in the art, the
present invention significantly reduces the manufacturing and
materials costs and the labor associated with running multiple
discrete wires to an outside electrical module. By instead using
one or two wires to transmit control signals to a plurality of
different electrical components, a vehicle may be more easily
upgraded. For example, multi-functional after-market outside
rearview mirror assemblies could readily be installed on a vehicle
using the communication system of the present invention since no
additional wires would need to be run to provide control of the
various additional functions provided in such a mirror assembly.
Further, the ability to offer various options in an outside
rearview mirror assembly is simplified since the wiring for each
vehicle would be the same. In addition, the communication system of
the present invention opens the door for additional advanced mirror
functions in the future.
By avoiding the need to run the vehicle CAN or J1850 bus to the
outside mirror assembly, multiple functions can be provided in an
outside mirror assembly without introducing security risks or
creating any added burden on the CAN or J1850 bus. The
communication further improves self-diagnostics and the ability to
test, trouble shoot, and repair the mirror assembly.
Another advantage to configuring an outside rearview mirror
assembly in the inventive manner described above is that the
printed circuit board (PCB), on which the mirror module and
electrical component circuitry is mounted, generates more heat than
the circuitry used in current commercially available mirror
assemblies. This generated heat may be "dumped" to the mirror
heater thereby reducing the number of heater wires in the heater
element, which reduces the cost of the heater element and enables
special glass technology requirements to be accommodated.
The above description is considered that of the preferred
embodiments only. Modifications of the invention will occur to
those skilled in the art and to those who make or use the
invention. Therefore, it is understood that the embodiments shown
in the drawings and described above are merely for illustrative
purposes and not intended to limit the scope of the invention,
which is defined by the following claims as interpreted according
to the principles of patent law, including the doctrine of
equivalents.
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